No matter how loudly fans sing of Cracker Jack, junk food is striking out in professional baseball. The Rays are among a growing number of major league baseball teams encouraging players to lay off the sugar and grease.

For the ballplayers, whose muscles can command multimillion-dollar contracts, the push for sound nutrition has more to do with performance and recovery than deflating a spare tire. Could you hit a double in the bottom of the ninth on an empty stomach?

Yet, like so many of their fans, some Rays players are finding that eating right is not always a walk in the ballpark.

While he has bought into the nutritional program, others still smuggle in their greasy bags. But here's food for thought: The nutritionist working with the Rays in recent years has also dished dietary advice for another team. They met the Rays last year in the World Series.

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When the Rays travel, they send a note asking for certain foods to be removed from the clubhouse before their arrival.

"There was a time when we'd bring in after-batting-practice cheeseburgers and big juicy cheesesteaks," said Chris Westmoreland, home clubhouse manager for the Rays. "That's been replaced with healthier items."

These days, the menus feature lean meats, fish and whole wheat pasta — topped with marinara sauce, please, not cream-based Alfredo sauce. Player preparation, Westmoreland notes, involves more than hitting and catching fly balls. It's also ensuring they eat well before and after the game.

Fruits, nuts and seeds are among the acceptable snacks. Although some players think the goal is watching waistlines, they can eat as many calories as they want. The organization just wants them to be good ones.

"I'd much rather see a player eating dark chocolate-covered raisins than eating gummy bears," said Cynthia Sass, the registered dietitian working with the Rays.

Dark chocolate is rich in antioxidants and has a type of fat that can help improve the athletes' circulation, she explained. And controlling blood sugar swings — like those gummy bears' highs and lows — helps the players have sustained energy throughout a game.

"Baseball is a sport where you need to be strong and have a lot of power, but you also need to have a lot of agility, think really quickly and react in a split second," she said.

Food plays a big role, she said, not just in preparing for the big game, but also in repairing muscle when it's over.

That's not a message that has reached everyone in baseball. But Boston Red Sox team nutritionist Tara Mardigan estimates that at least half the teams in major league baseball have dietitians.

And while she couldn't reveal the details of the program in Boston, she said a good diet doesn't need to be confusing and complicated — whether you're a player or a fan.

"The basics of what Mom and Dad told you are true: Eat your fruits and vegetables," she said. "If there's a way to make those sexy, I wish we could."

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Pitcher James Shields doesn't want to eat completely unhealthy meals, but he thinks it's okay to want a cheeseburger sometimes when you burn as many calories as he does on a daily basis.

"I'm not a supermodel, you know what I mean," he said.

But leftfielder Carl Crawford credits the Rays program with helping him to see the value of turkey burgers, whole wheat bread and drinking a lot of water. "I feel like I have more energy," he said. "Definitely."

Then there's Matt Garza, who brings in Popeyes fried chicken before games when he's the starting pitcher. He likes the meal with red beans and rice. Sometimes, a biscuit, too.

"I think we're all adults and could make our own decisions about what we want to eat," said Garza, who nonetheless admits he's better off not eating a lot of sugar. He also has a chef at home who helps him with nutrition.

Today's players may not realize how good they have it. When Don Zimmer was with the Brooklyn Dodgers in the 1950s, players were expected to show up to play, not to eat, he said.

After batting practice, Zimmer would have a clubhouse kid sneak a hot dog into his glove. Once he got caught slipping around a corner to wolf it down. He was fined $50.

Old habits die hard. Zimmer, now a senior adviser for the Rays, still traffics illicit dogs when in town for home games. But he no longer worries about being caught.

They're for the manager.

"Coney Island chili dogs are the finest," said Joe Maddon, referring to the venerable St. Petersburg hot dog establishment. He sees no conflict between his beloved treat and his support of the team's nutrition program.

"I actually think there's a tremendous amount of nutritional value to those chili dogs. I'll argue that with anybody."

Times staff writer Marc Topkin contributed to this report. Letitia Stein can be reached at lstein@sptimes.com or (813) 226-3322. For more health news, visit www.tampabay.com/health.

Fast facts

Myth buster

Rays' nutritionist Cynthia Sass on sports nutrition lore:

Carb loading: "Both the research and my experience in working with athletes shows that carbohydrate loading, let's say the night before an event, is not as effective as just eating a high-carb diet all the time." She advocates that athletes eat a range of complex carbs, including whole grains.

Protein: "That's probably the biggest one that I see. People think that they need more protein than they actually need and they may eat excessive amounts of protein. That's not good for many reasons."

Vitamins: "Sometimes I meet with athletes who are taking mega, megadoses of vitamins and minerals and they think that more is better, and it really isn't. It's really about balance."